SGER: NEESR Payload Project for NSF Award 0420347 - Control of Plastic Hinging Behavior of RC Bridge Systems

[摘要]0532084sger：美国国家科学基金会（NSF）奖0420347号NEESR有效载荷项目- RC桥梁体系塑性铰行为的控制本NEES研究（NEESR）有效载荷项目的重点是通过对桥梁体系在多重激励（包括节点和基础柔性的影响）下的大规模试验中的实际铰行为进行研究，准确模拟和控制混凝土桥梁结构中的塑性铰位置。传统上，用于表示钢筋混凝土系统中铰接行为的模型，以及由此产生的对不同加载条件下这种行为的理解，受到用实验数据验证模型的能力的限制——要么来自内部加固不足的已有桥梁结构，要么来自无法模拟现实边界条件的组件测试。这些详细模型的验证现在可以通过NEESR项目CMS-0420347收集的数据进行，该项目将对四跨大型桥梁系统的抗震性能进行调查，其中包括在内华达大学里诺分校（UNR）的NEES设备站点的基础和桥台处的土壤-基础-结构相互作用效应。拟议的NEESR有效载荷研究将分两部分进行：(1)对UNR NEESR团队现有的实验程序进行小的补充，以额外的仪器、非侵入性摄影测量方法和额外的地面运动输入（在低水平激励下）的形式，以及(2)对桥梁系统中塑料铰位置控制中接缝和基础灵活性和载荷历史的影响进行分析调查。该项目的具体目标如下：(1)使用传统的钢筋和混凝土测量仪以及摄影测量方法精确跟踪铰链区域和梁柱节点的变形；(2)使用OpenSees创建桥梁系统模型，捕获不同激励水平下的节点变形和塑性在柱单元中的传播；(3)将传统测量仪捕获的变形与摄影测量方法确定的变形进行比较。(4)对具有不同刚度和强度特性的桥梁系统进行参数化分析，以确定对非弹性行为、组件和系统性能的影响；(5)推荐计算桥梁系统漂移响应的简单技术，考虑关节灵活性和更准确的塑性铰行为；(6)在项目的测试阶段，通过研究生课程的内容和远程呈现的参与，吸引研究生和本科生。智力优势：本提案解决了单元和系统级非弹性变形的估计，考虑了钢筋混凝土桥梁系统在各种强地面运动要求下的接缝和基础灵活性的影响。作为这项工作的一部分，将为OpenSees平台开发一种改进的钢筋混凝土桥梁系统接缝模型。随着对单元中节点柔性和非弹性行为的贡献的更好理解，结构系统的漂移响应将得到估计。更广泛的影响：该项目拓宽了NEESR奖项的重点，该奖项评估了钢筋混凝土桥梁系统和新型铰接装置的土壤-基础-结构相互作用，以及节点灵活性对桥梁元件中铰接的发展和位置的贡献。本科生和研究生将在测试和研究生课程中通过网真参与工作。

Abstract0532084SGER: NEESR Payload Project for NSF Award #0420347 -Control of Plastic Hinging Behavior of RC Bridge SystemsThe focus of this NEES Research (NEESR) payload project is to accurately model and control plastic hinging locations in concrete bridge structures through an investigation of actual hinging behavior in large-scale testing of bridge systems subjected to multiple excitations that includes the effects of joint and foundation flexibility. Models that are created to represent the hinging behavior in reinforced concrete systems, and the resulting understanding of this behavior under different loading conditions, have traditionally been limited by the ability to validate the model with experimental data - either from pre-existing bridge structures with inadequate access to internal reinforcement, or from component tests that are unable to simulate realistic boundary conditions. The validation of these detailed models is now possible with the data that will be collected during the NEESR project CMS-0420347 investigation of the seismic performance of four-span large-scale bridge systems, which includes the soil-foundation-structure interaction effects at the footings and abutments, at the NEES equipment site at the University of Nevada, Reno (UNR). The proposed NEESR payload research will be conducted in two parts: (1) small additions to the existing experimental procedure of the UNR NEESR team in the form of additional instrumentation, non-invasive photogrammetric methods, and additional input ground motions (at low level excitation), and (2) an analytical investigation of the effects of joint and foundation flexibility and load history on the control of plastic hinging locations in bridge systems. The specific goals of the project are the following: (1) accurately track the deformations in the hinging region and beam-column joints using traditional reinforcement and concrete gages as well as photogrammetric methods, (2) create a bridge system model using OpenSees that captures the joint deformations and spread of plasticity in the column elements under different levels of excitation, (3) compare deformations captured using traditional gages with those determined using photogrammetric methods, (4) perform parametric analysis of bridge systems with varied stiffness and strength properties to determine the effect on inelastic behavior, component, and system performance, (5) recommend simple techniques for calculating the drift response of bridge systems considering joint flexibility and more accurate plastic hinge behavior, and (6) engage graduate and undergraduate students through content in graduate courses and participation by telepresence during the testing phases of the project. Intellectual Merit: This proposal addresses the estimation of element and system level inelastic deformations considering the impact of joint and foundation flexibility for reinforced concrete bridge systems subjected to various strong ground motion demands. As part of this work, an improved joint model for reinforced concrete bridge systems will be developed for the OpenSees platform. The drift response of structural systems will be estimated with a better understanding of the contributions of joint flexibility and inelastic behavior in the elements. Broader Impacts: This project broadens the focus of a NEESR award that evaluates soil-foundation-structure interaction of reinforced concrete bridge systems and new hinging devices, to the contributions of joint flexibility to the development and the location of hinging in bridge elements. Undergraduate and graduate students will participate in the work through telepresence during testing and through graduate coursework.